Lift truck with a horizontally and pivotally movable mast assembly



A wfi m, 1967 LIFT TRUCK WI TH A HORIZONTALLY AND PIVOTALLY MOVABLE MAST ASSEMBLY Filed April 23, 1965 L S. MATHEW ET AL 5 Sheets-Sheet 1 %,f/ AWONEK A M-ii Ill, 1957 MATHEW ET Al. 3,313,436

LIFT TRUCK WITH A HORIZONTALLY AND PIVOTALLY MOVABLE MAST ASSEMBLY Filed April 25, 1965 5 Sheets-Sheet 2 Fig.4.

$211M s M 477oM/E)g- Aprrfl M, 1967 L. s. MATHEW ETAL 3,313,436

LIFT TRUCK WITH A HORIZONTALLY AND PIVOTALLY MOVABLE MAST ASSEMBLY Filed April 23, 1965 5 Sheets-Sheet 5 H --s Fig. 6.

United States Patent 3,313,436 LIFT TRUCK WITH A HORIZONTALLY AND PTVOTALLY MOVABLE MAST AS- SEMBLY Leonard S. Mathew, Kingswood, Surrey, and George W. A. Chapman, Horley, Surrey, England, assignors to Matbro Limited, Horley, Surrey, England, a British company Filed Apr. 23, 1965, Ser. No. 450,288 Claims priority, application Great Britain, Apr. 29, 1964, 17,8?4/64 3 Claims. (Cl. 214-672) The present invention relates to fork lift trucks of the type adapted to be loaded either at one side of the machine or at the front of the machine.

A fork lift truck which has forks which may be employed alternatively for loading at the front of the machine and at one side of the machine, has great utility for operation in restricted spaces, particularly in the alleys in a factory or warehouse and is desirably constructed so as to have a small overall length to make it as maneuverable as possible.

The mast of a fork lift truck includes a stationary guide, which does not move in the vertical direction, a moving guide, which moves up and down the stationary guide, and a carrier frame, which moves up and down the moving guide. The carrier frame usually moves at twice the rate of the moving guide and means are provided for tilting the carrier frame backwards after loading, so that a load supported on forks, carried by the carrier frame, does not slip ofl forward. The tilting movement of the carrier frame can be produced either by tilting the whole mast or alternatively the carrier frame can be tilted in relation to the mast, which itself remains vertical. In the lift truck of the present invention either of these alternatives may be used.

The stationary guide of the mast of a fork lift truck usually extends down to a position close to the ground, so so as to receive the thrust that may require to be exerted during the insertion of the forks under a load. However, it has already been proposed to provide a lift truck with a swinging mast, in which the lower end of the stationary guide was above the level of the vehicle axis to permit a load, supported on the forks, to be swung around to lie lengthwise of the machine. This prior arrangement was intended for use when long loads, such as timber planks, steel pipes and steel girders, are to be transported.

According to the present invention a lift truck for front and side loading is characterised by a mast assembly which is mounted on a carriage for movement transversely of the machine along a horizontal guide approximately over the axis of the front axle (or the axis of the front Wheels, where there is no front axle as such), the mast assembly including a stationary guide, the foot end of which lies above the level of the horizontal mast carriage guide, a moving guide and a carrier frame, means for turning the mast about an axis substantially on the centre line of the mast to move the carrier frame between a forward-facing position and a sideways facing position, the moving guide of the mast and carrier flame being shaped to permit the carrier frame to be lowered down to ground level whilst straddling the horizontal mast carriage guide and front axle and front wheel of the lift truck and the frame of the lift truck being shaped so that there is a recess to the rear of the front axle to permit the carrier frame to be withdrawn laterally of the truck, when in the sideways-facing position, for a sufficient distance to bring the rearward lift fork wholly or substantially wholly within the frame of the lift truck. In practice this means that the front axle of the lift truck is connected to the rear axle and rear part of the machine by a narrow frame portion lying on the opposite side of the machine to that from which the forks may be extended.

Reference is hereinafter made to the accompanying drawings, partly diagrammatic in form, wherein:

FIGURE 1 is a plan View of a lift truck according to the present invention with the forks retracted in the sideways position.

FIGURE 2 is a similar view to FIGURE 1 with the forks extended, and

FIGURE 3 is a plan view with the forks in the forward position.

FIGURE 4 is a side view of the lift truck with the forks in the forward position.

FIGURE 5 is a diagrammatic representation of the means for traversing the mast carriage, and

FIGURE 6 is a side view from the opposite side showing the forks in the sideways position.

The fork lift truck shown in the accompanying drawings has a pair of side-by-side steerable rear wheels 1 and driven front wheel 2.. The rear wheels 1 may also be driven. The superstructure 3 of the machine is low so that loads may be carried at a low level when the forks are in the sideways position.

The front axle (not shown) supports a pair of channel members 4, which act as guides for the laterally moving mast structure. It will be seen that the main superstructure 3 of the machine, within which the electric drive motor and storage batteries are housed (or alternatively an internal combustion engine) is connected to the front axle structure at one side of the machine.

The mast structure comprises a carriage 5, having guide wheels 6, which engage in the channel members 4. The carriage 5 has a king post 7 rigidly secured to it. A stationary mast guide 8 has rearwardly projecting ears 9, which are pivotally attached to the king post 7 on the pivot axis 10. As can be seen from FIGURE 6, the foot end of the stationary guide 8 is above the level of the guides 4, which are themselves above the top of the wheel 2 in the illustrated construction.

The stationary guide 8 acts as a guide for a moving guide 11, which in turn acts as a guide for a carrier frame 12, which supports lift forks 14. The carrier frame 12 has a central cut-out portion to enable it to straddle the front axle, as shown in FIGURE 6.

The moving guide 11 and carrier frame 12 are moved vertically in any convenient manner and are preferably moved by means of a common hydraulic jack in the conventional way, so that the rate of movement of the carrier frame 12 is double the rate of movement of the moving guide 11.

The lateral movement of the mast support carriage 5 is preferably effected by means of a drive pulley 15, which can be driven to turn in both directions to drive a cable or chain 16, which also passes around an idle pulley 15. The cable or chain 16 is secured to a part 17 of the carriage 5.

The angular movement of the stationary guide 8 in relation to the king post 7 is preferably effected by a hydraulic jack. The carrier frame front plate 12 is preferably pivotally attached on a horizontal axis to its guides, which move up and down the moving guide 11 and may be tilted in the known manner by means of a hydraulic jack. Thus, all the movements of the various parts of the mast, except the movement of its carriage, are performed hydraulically and the necessary supply of hydraulic fluid is via flexible hoses, which trail from the mast.

It will be seen from FIGURES 1 and 6 that, with the carrier frame 12 facing sideways, the forks 14- may be lowered to ground level and the ends of the forks withdrawn to a position where they do not extend beyond the side of the machine. The forks 14 may then be extended to pick up a load as shown in FIGURE 2. The load is then raised to a level above that of the superstructure 3 before the carriage 5 is withdrawn to bring the load to a position between the wheels 2.

When the guide 11 has been raised to lift its foot end and the carrier frame 12 above the level of the mast carriage guides 4, the forks 14 can be swung from the sideways position to the forward position and vice-versa. It is therefore possible to approach a load of, for example, steel tubes, with the forks in the forward position shown in FIGURE 3, pick up the load, swing the mast to the sideways position, moving the mast carriage to the right (as seen in FIGURE 3) and lowering the load down to a height approximately'level with the top of the superstructure.

It will be seen that in this way there is provided a fork lift truck of great versatility and quite simple construction.

The king post 7 in the illustrated construction is located on the centre line of the mast. It may be located slightly off-centre, but essentially the arrangement of the king post and the mast is such that the carrier frame 12 straddles the front axle and wheel when the carrier frame 12 is lowered to ground level in the sideways-facing position. The centre line of the carriage guide, provided by the channels 4, is essentially in the same vertical plane as the axis of the front wheels 2, but may be located a short distance to the front or rear.

The middle of the carrier frame should also be substantially on the centre line of the carriage guide, so that the carriage may be traversed easily sideways-facing with the forks loaded. As may be seen the middle of the carrier frame may be several inches to the front or rear of the centre line of the carriage guide without disadvantage.

We claim:

1. A lift truck including a frame for front and side loading characterised by a mast assembly which is mounted on a carriage for movement transversely of the machine along a horizontal guide approximately over the axis of the front axle (or the axis of the front wheels, where there is no front axle as such), the mast assembly including a stationary guide, the foot end of which lies above the level of the'horizontal mast carriage guide, a moving guide and a carrier frame including forks, means for turning the mast about an axis substantially on the centre line of the mast to move the carrier frame between a forward-facing position and a sideways facing position, the moving guide of the mast and carrier frame being shaped to permit the carrier frame to be lowered down to ground level whilst straddling the horizontal mast carriage guide and front axle and front wheel of the lift truck and the frame of the lift truck being shaped so that there is a recess to the rear of the front axle to permit the carrier frame to be withdrawn laterally of the truck, when in the sideways-facing position, for a sufiicient distance to bring the rearward lift fork wholly or substantially wholly within the frame of the lift truck.

2. A lift truck according to claim 1 wherein the stationary guide is supported by and angularly movable about a stationary king post mounted on the carriage.

3. A lift truck according to claim 2, wherein the portion of the carrier frame supporting the forks is tiltable about a horizontal axis in relation to the king post of the mast.

References Cited by the Examiner UNITED STATES PATENTS 3,216,598 11/1965 McKee et al 214-660 FOREIGN PATENTS 7/1958 Germany. 1/1964 Great Britain. 

1. A LIFT TRUCK INCLUDING A FRAME FOR FRONT AND SIDE LOADING CHARACTERISED BY A MAST ASSEMBLY WHICH IS MOUNTED ON A CARRIAGE FOR MOVEMENT TRANSVERSELY OF THE MACHINE ALONG A HORIZONTAL GUIDE APPROXIMATELY OVER THE AXIS OF THE FRONT AXLE (OR THE AXIS OF THE FRONT WHEELS, WHERE THERE IS NO FRONT AXLE AS SUCH), THE MAST ASSEMBLY INCLUDING A STATIONARY GUIDE, THE FOOT END OF WHICH LIES ABOVE THE LEVEL OF THE HORIZONTAL MAST CARRIAGE GUIDE, A MOVING GUIDE AND A CARRIER FRAME INCLUDING FORKS, MEANS FOR TURNING THE MAST ABOUT AN AXIS SUBSTANTIALLY ON THE CENTRE LINE OF THE MAST TO MOVE THE CARRIER FRAME BETWEEN A FORWARD-FACING POSITION AND A SIDEWAYS FACING POSITION, THE MOVING GUIDE OF THE MAST AND CARRIER FRAME BEING SHAPED TO PERMIT THE CARRIER FRAME TO BE LOWERED DOWN TO GROUND LEVEL WHILST STRADDLING THE HORIZONTAL MAST CARRIAGE GUIDE AND FRONT AXLE AND FRONT WHEEL OF THE LIFT TRUCK AND THE FRAME OF THE LIFT TRUCK BEING SHAPED SO THAT THERE IS A RECESS TO THE REAR OF THE FRONT AXLE TO PERMIT THE CARRIER FRAME TO BE WITHDRAWN LATERALLY OF THE TRUCK, WHEN IN THE SIDEWAYS-FACING POSITION, FOR A SUFFICIENT DISTANCE TO BRING THE REARWARD LIFT FORK WHOLLY OR SUBSTANTIALLY WHOLLY WITHIN THE FRAME OF THE LIFT TRUCK. 